Almost everything we know about Millennial political attitudes tells us that Paul Ryan is not the sort of politician most of them are inclined to support. Their political experience would also tend to bias them against a Bush-era Republican such as Ryan. As Pew reports, those who came of age during the Bush-Obama years are much more likely to vote Democratic than the electorate as a whole. Overall, Millennials self-identify as conservative less than any other generation, and they self-identify as liberal more than any other. In addition to cultural and demographic changes that make Millennials less likely to vote Republican, their main experience with Republican governance was George W. Bush’s administration, which has understandably alienated them on several fronts.

[F]or the time being, there is scant polling data on the effect of Ryan's selection on younger voters, and experts on youth voting patterns warn that superficial impressions of a candidate often fade quickly. A candidate's age, in and of itself, has not been shown as a reliable indicator of how younger voters cast their ballots in past elections.